Rising sea temperatures and global warming--do they impact an increase in tornadic activity, hurricanes and flooding, or is it "normal weather variability?"

This year, we've seen the fastest start for tornadoes since 1999. Warm temperatures and dry conditions during the winter kept water temperatures warm in the Gulf of Mexico. The warm, moist air from the Gulf then combined with weather systems moving eastward into the central U.S., creating good conditions for tornadic activity. "Tornado Alley," a stretch of land from Texas to North Dakota, is ideal for tornadoes because dry polar air from Canada meets warm moist tropical air from the Gulf.

With flooding, there are meteorological variables like snowpack, temperature, precipitation distribution and the strength and location of the jet stream; natural factors, such as soil permeability, initial soil moisture content, ground slope, ground cover and basin size and shape, and the activities of people such as paving, clear cutting, road building, farming, stream channelization, and levee and dam building. Flooding last year was unusually severe, and while some statistical evidence indicates the magnitude of floods is increasing, it remains difficult to prove an increase because of the natural variability of rainfall and runoff.

Per researchers, the number of major hurricanes worldwide has nearly doubled over the past 35 years, though the total decreased. During the same period, average tropical sea surface temperatures increased as much as 1 degree. So are rising sea temperatures, then, linked to more intense storms? No one's sure. They believe greenhouse warming plays a part, and that warmer seas spawn more intense hurricanes, but won't say it's the whole picture. Some believe the growing violence reflects a natural weather pattern that spans decades, and don't link it to global warming at all. And so it remains, the relationship between global warming and hurricane strength, are still a topic of controversy.